Process and apparatus for mixing



PROCESS AND APPARATUS FOR MIXING Filed Nov. 17, 1958 44 4o L- INVENTOR.

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3 TTO NEY United States Patent 3,051,452 PROCESS AND APPARATUS FORMIXING Leendert Nobel, Arnhem, Netherlands, assignor to American EnkaCorporation, Enka, N.C., a corporation of Delaware Filed Nov. 17, 1958,Ser. No. 774,305 Claims priority, application Netherlands Nov. 29, 19577 Claims. (Cl. 2594) This invention relates in general to the mixing offlowing streams of gaseous, liquid and/or granular media through the useof stationary bafiles or pipe restrictors providing a tortuous flow pathand more particularly to a process and apparatus for combining materialsto be homogenized into a main stream and for displacing portions of thismain stream relative one to the other in a specific manner.

It is generally known in the mixing art to divide a main stream ofmaterial to be homogenized into two concentric partial streams orsectors, to displace these concentric sectors relatively through the useof helically shaped stationary baffies, and to recombine the displacedsectors, after which the operation may be repeated if necessary ordesired. For example, see French Patent No. 735,033.

In another known system, a main stream of rectangular cross-section isdivided into a plurality of sectors, also of rectangular cross-sections,after which the individual sectors are shifted one relative to the otherand reunited into the original rectangular cross-section without changein the dimensions thereof. This system is shown in German Patent No.358,018.

The two systems described above are quite similar in operation to theshifting of pieces on a chessboard, wherein any arrangement may beobtained either by interchanging two of the pieces, or by a completeseries of interchanges, but neither of Which includes exchangingportions of adjacent pieces. By proper selection of the flow rate in theoperation of these systems, a high turbulence may be produced within thebaffles, Which turbulence contributes substantially to the mixing orhomogenizing action.

The processes described above, however, have many disadvantages and donot operate satisfactorily in certain applications. For example,although mixing does occur to some extent between adjacent sectors, andthe reunited stream therefore may not be of uniform consistency.Moreover, the required or proper flow rate mentioned supra increasesdirectly in proportion to the viscosity of material to be mixed.Consequently, it is often impossible to convey highly viscous materialthrough the baffles at a rate necessary to produce the desiredturbulence. Furthermore, even if the high flow rate Were possible, thesame would lead to excessive strains or forces on the somewhat delicatebaffle plates and thereby prohibit use for homogenizing highly viscousmaterial.

One of the objects of this invention, therefore, is to provide a mixingprocess and apparatus not having the disadvantages of known systems.

Another object of the present invention is to provide a mixing processand apparatus not dependent upon turbulence for satisfactory operation.

Still another object of this invention is to provide a mixing processand apparatus not dependent for satisfactory operation upon excessive orextremely high flow rates.

A further object of the present invention is to provide a process andapparatus for thoroughly homogenizing a flowing stream of two or morematerials regardless of the viscosity.

An additional object of this invention is to provide a stationary mixingapparatus for homogenizing a flowing "ice stream of two or morematerials which may be economically manufactured and easily maintained.

In accordance with the present invention, two or more flowing streams ofmaterials are combined into a main stream, after which the main streamis divided into a plurality of sectors having a first shape incross-section. Thereafter, the individual sectors are shifted relativeto one another simultaneously with an alteration in crosssection to asecond shape overlapping two or more of the original sectors, andtemporarily recombined. Subsequently, the temporary main stream is againdivided into sectors which may correspond in shape to, but whichconsists of portions of material obtained from two or more of, thefirst-mentioned sectors. It can be seen, therefore, that each subsequentsector formed by division of the main stream will contain material fromat least two previous sectors intermixed in a preceding operation. Theprocedure may be repeated, if necessary, until thorough mixing has beenobtained.

Whereas in the known systems described hereinabove only the firstdisplacement of sectors changes the overall pattern with respect to themain stream, and subsequent shifting only intensifies the mixing ofmaterial in each individual sector, each exchange of material betweenadjacent sectors in accordance with this invention contributes directlyto mixing of the entire main stream. The reason for this is that eachsector formed after a division of the main stream will contain a smallquantity of material from at least two of the preceding sectors. As themixing operation continues, a sector will receive progressively smallerquantities from each of a progressively larger number of previoussectors. In the last analysis, theoretically at least, each final sectorwould receive an infinitesimal amount of material from each of aninfinite number of preceding sectors, since the number of contributingsectors after each division of the main stream increases exponentially.In practice, however, a sufficiently fine dispersion of the media in themain stream is obtain after a few divisional operations such asdescribed.

There are, of course, a number of ways in which the principles of thisinvention may be carried out in order to insure that each subsequentsector receives material from a number of preceding sectors. It ispreferred, in accordance with this invention, that the cross-sectionalshape of each sector be elongated during the relative displacement ofadjacent sectors, with a corresponding reduction in height in order tomaintain the same overall area throughout. Consequently, if the exit ordischarge end of a sector is superimposed upon the entrance of themixing apparatus, it can be seen that the elongated crosssectional shapewill overlap not only its own entrance end but also the entrance end ofat least two adjacent sectors. An additional advantage to this processis that the various materials to be mixed in the adjoining sectors havea greater area of contact with one another after reuniting, whichpromotes homogenizing of the main stream by diffusion of the materialsinto one another.

Although the cross-sectional shape of materials contained in the mainstream prior to division into sectors could be rectangular, square, orany other desired configuration, it is preferred that one of thematerials be closed upon itself in order to eliminate many of thedisturbing edge effects. This may be obtained by forming the supplystreams of the materials to be mixed into an initial main stream ofannular cross-section and by reuniting the homogenized material into asubsequent main stream having the same cross-sectional area as theinitial stream. Moreover, it is preferred that the supply streams of thedifferent materials be disposed in such a manner that the main streaminitially formed by introduction of one material into the stream of theother will consist of concentric 3 annular portions. An advantage tothis treating system is that more uniform heating or cooling can beaccomplished if such is necessary or desired.

Although the annular stream of one material may be fed either radiallyor axially into the annular stream of the other materials, it has beenfound that a more satisfactory mixing is obtained if the supply streamsare combined when flowing generally in the same direction. Statisticshave shown that a uniform distribution of the media over the main streamis obtained more rapidly in this manner than by random commingling f thesupply streams.

The process described immediately hereinabove is particularly wellsuited for mixing media whose quantities are of substantially the sameorder of magnitude. Difliculties may be encountered, however, if one ofthe materials consists of a high viscous liquid and the other a pigmentwhich is to be mixed in small proportionate amounts.

Mixing of material in a disproportionate ratio may be accomplished inaccordance with this invention by shunting a small portion of the highviscous main stream, adding the pigment or other material to the shuntedstream, and recombining the shunt stream into the main stream by the useof one or more pumps. This process per se is not a part of the presentinvention but forms the claimed subject of companion application SerialNo. 655,004, filed April 25, 1957, now Patent No. 2,929,731 owned incommon with this application. This main stream may then be subdividedinto sectors for homogenizing in the manner stated above.

Aside from the mixing of high viscous liquids and pigmerits, thisinvention also relates to the homogenizing of flowing gases, liquidshaving similar or different properties, or granular materials other thanpigments. The apparatus contains no moving parts and consistsessentially of a supply line, a discharge line, and at least two mixingmembers disposed therebetween. At least two longitudinal channels shouldbe provided in each mixing member to permit division of the supply intosectors, displacement of sectors, and alteration of cross-section asdescribed previously. The discharge end of a channel should berearranged or displaced not only with respect to the correspondingentrance end of that particular channel, but also with respect to otherchannels in that mixer.

A very successful mixing action may be obtained if a plurality ofidentical mixers are placed in series in a suitable mixing zone or tube,and if the baffles are constructed so as to alter the main stream from aplurality of sectors arranged in a single row at the entrance end torelatively displaced oblong or elongated sectors arranged in twoparallel rows at the discharge end. As stated earlier, the sectors couldhave any desired cross-sectional shape. In accordance with thisinvention, however, one dimension of the sector at the entrance endshould be reduced by about half at the discharge end, while the otherdimension should be doubled during the alteration in shape in order tomaintain constant the cross-sectional area. One satisfactory manner inwhich this alteration may take place is through the use of a transitionzone substantially midway between the entrance and discharge ends of thelongitudinal channel defined by each pair of baflles. In the first partof the channel one dimension may be reduced by half while the other iskept constant, and the other dimension may be doubled during the secondpart of the channel while the reduced dimension is maintained constant.

Although the sectors discussed above could be rectangular, square, etc.,it is preferred according to this invention that ring-like sectors beformed by dividing an annular stream radially into components disposedabout the periphery thereof, or consecutive peripheral channels. Eachsector or channel therefore may be defined in cross-section at theentrance end of a mixer by an outer curved surface, an inner curvedsurface, and a radial surface on each side. The annular stream should bedivided into a plurality of such sectors, each having the same shape anddimensions in cross-section. The material passing through a firstchannel should be displaced outwardly to occupy a space having only halfthe original radial length but twice the original circumferentiallength. That material passing through channels immediately adjacent tothe first-mentioned should be displaced inwardly also to occupy a spacehaving only half the original radial length but twice the originalcircumferential length, and so on throughout the annlar stream.Consequently, the annular stream is divided into consecutive radialsectors upon initial contact with a mixer, but emerges from the mixer inalternate outer and inner sectors of reduced radial dimension butdoubled circumferential dimension, which not only displaces one sectorradially with respect to adjacent sectors but also compresses the layersconstituting the supply of material to be mixed and spreads the sameover a greater circumferential area. This system operates mosteffectively if the materials to be mixed are supplied in two concentricannular streams to form a main stream of annular cross-section prior tointroduction into the first mixer unit.

Other objects and advantages of this invention will become evident uponstudy of the following detailed disclosure of a preferred embodimenttaken in conjunction with the accompanying drawings, wherein FIGURE 1 isa perspective view of one mixer unit suitable for use in accordance withthe principles of this invention, with the discharge end facing theviewer;

FIGURE 2 is a sectional view taken along the lines 22 of FIGURE 5illustrating the entrance of two representative sectors from concentricannular streams of material into a mixing apparatus containing a mixerunit such as shown in FIGURE 1;

FIGURE 3 is a sectional view taken along the lines 33 of FIGURE 5illustrating the combined alteration in shape and relative displacement,both radially and circumferentially, produced by the first mixer unitupon passage of the aforesaid two representative sectors therethrough;

FIGURE 4 is a sectional view taken along the lines 4-4 of FIGURE 2illustrating the radial displacement only of streams passing through twoadjacent sectors of a single mixer unit; and

FIGURE 5 is a schematic view, partially in section, illustrating acomplete mixing apparatus including a plurality of the mixer units shownin FIGURE 1, suitable conduits for supplying two different materials inconcentric annular streams, and a discharge conduit for combining theblended streams into a main stream and for feeding the same to otherprocessing apparatus, not shown.

With attention first directed to FIGURES 2 and 3, a further explanationof the change occurring during passage of material through one mixingstage will be given. In these figures reference numeral 10 represents anouter tubular conduit within which the mixer unit 11 is snuglypositioned. An inner tubular conduit 12 completes the assembly andtogether with conduit .10 defines an annular passageway which receivesthe mixer unit.

At the outset it shoud be pointed out that a plurality of mixer units11, preferably of identical construction mounted either in staggered oraligned relationship, are placed in series between the outer and innerconduits 10, 12, as shown in FIGURE 5. For purposes of illustration theouter layer or annular ring of material 13 has been cross-hatched toindicate red pigment and the inner layer or annular ring 14 has beencross-hatched for liquid, although it should be understood that thisinvention is not limited to the mixing of two materials only, to themixing of pigment with liquid, to division into the precisecrosssectional shapes shown, or to mixing of materials in the ratioshown.

Although only two sectors or channels 15, 16, as shown in FIGURE 2 are*filled with material to be mixed, it is pointed out that the entireannular zone between the outer and inner conduits is filled withmaterial flowing normally into the plane of the figure. The two sectors15, 16 are separated from each other by one of the plurality of radialbafiles 17 disposed circumferentially around the mixer unit 11 and fromother radial sectors by the other baflles, as shown. By means to bedescribed shortly, the radial sector 15 is shifted or displaced from theFIGURE 2 position to the outer position shown in FIGURE 3. During thetransfer from the FIGURE 2 to the FIGURE 3 position this sector wasaltered in cross-section from a generally elongated shape in a radialdirection to one elongated in a circumferential direction. In otherwords, the major axis of the sector extends circumferentially and theminor axis extends radially, which is a reversal of the initialconfiguration where the major axis extended radially and the minor axisextended ciroumferentially. This changed shape inherently produces areduced thickness of the layers 13, 14, but spreads them over asufliciently greater circumferential portion to maintain a constantcross-sectional area. The flattened discharging sector 15 of FIGURE 3 issymmetrically disposed about the more squarely shaped sector enteringthe mixer in FIGURE 2, as can be detected by comparison of the figuresor upon consideration of the outlets shown in dotted radial lines inFIGURE 2.

Simultaneously with the passage of sector 15 through the mixer unit 11,adjacent sector 16 undergoes a similar transition, but in this case istransferred inwardly as evidenced by the FIGURE 3 position.Consequently, the consecutive sectors 15, 16 entering the mixer as fullradial segments of the annular main stream of materials are transformednot only into different shapes but also into inner and outer sectorsstaggered one with respect to the other. The inner and outer components15, 16 emerging from the mixer are radially separated, at leasttemporarily until complete discharge from this particular mixer, by aring-like divider 18 which forms a base for the remaining elements ofthe mixer unit, which will be discussed presently. This divider 18 is sodisposed with respect to said other elements of the mixer that thestreams of liquid entering adjacent sectors such as 15, 16 are equallydivided and have substantially the same radial dimension in the FIGURE 3position.

If the baffles 17 on the immediately subsequent mixer unit 11 are inalignment with the first mixer shown in FIGURES 2 and 3, a portion fromeach of the two sectors 15, 16, as well as from sector 20, will form thesquareshaped entrance sector for this second mixer, as illustrated bybracket 21 in FIGURE 3. The material discharging from this portion ofthe second mixer unit 11 will be identical in cross-section to thesector 15, and located in the same position relative to the mixer, butwill be composed of four layers 13, 14, 13, 14, since the bafiles 17, 17will remove a slice from the full radial distance between conduits 10,12, which of course includes a part of the outer sector 15 and parts ofadjacent inner sectors 16, 20. In this manner of operation, materialfrom adjacent channels actually is inter-mixed during each passagethrough a mixer unit. This of course contributes to homogenization ofthe main stream forming the concentric annular streams.

With the balfles 17 on successive mixer units in alignment as mentioned,the material channelled into the second mixer will contain an equalportion from each of sectors 16, 20, and a portion from sector 15 aboutequal to the total from sectors 16, 20. Staggering of baffies onsucceeding mixers will result in changing the quantity of materialremoved from one preceding inner sector relative to the other innersector. This effect is the same as shifting the bracket 21circumferentially about the tubular conduits. 'It is apparent,therefore, that a consistently uniform interchange of material from thegreatest number of preceding sectors can be obtained if the mixers aremounted in alignment, although exchange of material from at least twopreceding sectors is possible even if the mixers are staggered one withrespect to another.

The preferred apparatus for performing the foregoing functions will nextbe described, with particular attention directed to FIGURE 1. As statedearlier, the discharge end of mixer unit 11 appears in the foreground,with the entrance end of course in the background. The unit 11 isprovided with twelve baflles 17 as shown, each baffle extending radiallyfor a sufficient distance to bridge the space between outer and innerconduit-s 10, 12, when the mixer is installed therein. The baffles 17operate in pairs to divide the supply stream in a manner fully explainedhereinabove.

Formed integral with or secured in any suitable manner to the dividerring 18 are two concentrically disposed circular rows of projectionseach of which facilitates the transition of individual channels from theFIGURE 2 position to that shown in FIGURE 3 and separatescircumferentially adjacent sectors. 'One row of separators extendsinwardly from the divider '18 and the second row, staggered with respectto the first, extends outwardly. The outermost, or outer, separators 22consist essentially of a solid body portion 23 which is wedge-shaped andterminates at the discharge end in a sharp edge 24 extending generallyradially of the mixer. The wedge-shaped body portion 23 of separators 22provides faces 25, 26 which slope in such a manner as to permitflattening of the stream of material flowing through a sector defined bytwo adjacent separators 22, 22. The leading end of body portion 23 isprovided with a sloping face 27 (see also FIGURE 4) which deflects afull radial segment inwardly into the elongated discharge end of themixer to form inner sectors such as 16, 20 in FIGURE 3.

The inner separator-s 28 are substantially identical to the outerseparators with the same wedge-shaped body portion and sharp trailingedge, but operate to deflect alternate full radial segments outwardly toform sectors such as 15 in FIGURE 3. These inner separators 28 arewedge-shaped at the trailing end 30 and have sloping faces 31, 32similar to the faces 25, 26 on the outer separators. Moreover, eachinner separator is provided with a sloping surface 33 at the entranceend, also as shown more clearly in FIGURE 4.

With attention directed to 'FIGURE 4, it can be seen that materialflowing into the sector 16 follows the direction of arrow 34 and isdisplaced downwardly by the sloping surface 27 on the body 23 of theouter separator. On the other hand, material entering into the sectorimmediately adjacent to 16 follows the path illustrated by arrow 35 andis deflected outwardly by the sloping surface 33 on the body 30 of theinner separator 28. This operation of course is repeated throughout themixing apparatus, it being pointed out that the transition shown betweenFIGURES 2 and 3 occurs simultaneously with the reduction in thicknessillustrated by FIGURE 4. It will be appreciated from the foregoing thatthe number of layers of material is doubled during the passage througheach mixing unit, but that the thickness of individual layers of coursewill simultaneously be reduced and spread over a larger areacircumferentially around the units 11.

If, for example, ten mixer units are arranged in series, and thethickness of each of the entering layers of colored and uncoloredmaterial is assumed to be 1 cm., then the thicknesses of the layersdischarging from the apparatus will be reduced to 0.01 mm. Consequently,the main stream will be rapidly homogenized by diffusion of the mediainto one another upon overlapping of adjacent sectors.

Attention is now directed to FIGURE 5, which illustrates a preferredmanner in which two concentric streams may be blended initially into amain annular stream for introduction into a mixing apparatus such asdescribed above. In this figure, fifteen mixer units are positioned inseries within the outer tubular conduit 10' and the inner tubularconduit 12, although only four are shown. A main conduit 36' suppliesviscose, in this example, to the mixing apparatus, and a container 37furnishes the red pigment chosen for discussion. In order to introducethe pigment into the' viscose in the manner fully explained 7' byaforesaid application Serial No. 655,004, it is preferred that a portionof the viscose stream be shunted and combined with a portion of thepigment, after which the highly concentrated viscose-pigment solutionmay be combined with the main viscose supply.

The procedure for mixing the pigment will not be described in detailherein. Suifce it to say that a portion of viscose from supply conduit36 is shunted through pipes 38, 40mm annular compartment 41. Pumps 42,43 are provided for performing this operation, and for introducing thepigmented viscose into the compartment '41. The pump '43 must have ahigher capacity than that of pump 42, of course, in order to accommodatethe increased volume of material caused by initially combining theViscose and pigment, also as explained in said copending application.

Annular compartment 41 surrounds the widened portion 44 of supplyconduit 3-6, as shown in FIGURE 5, and provides the outer annular streamcross-hatched as red pigment in FIGURE 2. The portion 44 of conduit 36supplies the inner annular stream represented as liquid in this figure.If desired, steel wool or other porous material 45 may be packed withinannular compartment 41 to insure thorough preliminary mixing of theshunted viscose and pigment. This material of course could be eliminatedif such preliminary mixing were not necessary or desired, for example,when mixing two materials having approximately the same consistency.

Moreover, in the event that the longitudinal dimension of thecompartment 41 and portion 44 of supply conduit 36 is not sufficientlylong to align the two layers as shown in FIGURE 2, it may be desired toadd flow straighteners 46. Four of these straighteners have been shownin FIG- URE 5, but of course the number depends on the length ofcompartment 41, portion '44, and the turbulence of the materialintroduced into the mixing apparatus. After passage through the mixerunits 11, the blended material flows through terminal portion 47 of theapparatus which eventually converges into a continuation of the mainconduit 36, illustrated at 48.

With the foregoing discussion in mind, it will be apparent that a streamof viscose may be supplied through conduit 36 into the mixing apparatus.This viscose diverges as indicated by arrows (see FIGURE 5) and flowsinto the widened portion 44. In the meantime, a portion of viscose hasbeen shunted through pipe 38, is preliminarily combined with pigment fedfrom container 37 by pump 42, and is finally forced into the annularcompartment 41 by second pump 43.

The two annular streams emerge from the compartment 41, and widenedportion 44, respectively, in concentric layers, and pass through theilow straighteners into the mixer units proper. The annular streams areintroduced into the first mixer 11 in the manner shown at 13, 14 byFIGURE 2, and are discharged from this mixer as shown in FIGURE 3 witheach sector flattened, or reduced in one dimension while being elongatedin the other. Thereafter, the materials are passed directly into asecond mixer unit 11 which divides the streams into another twelveradial sectors illustrated by bracket 21 in FIGURE 3. These sectors alsoare flattened as described above, and pass directly into a third mixerunit. The four concentric streams discharging from second mixer unit 11are of course doubled so that eight concentric streams emerge from thisthird mixer. This process is repeated, in the example given, until thematerial flows through fifteen different mixers. It will be appreciatedthat the thickness of the layers 13, 14 originally introduced throughcompartment 41 and portion 44, respectively, is repeatedly reduced to aminute amount and the mixture discharging through terminal portion 47 isthoroughly blended. Materials other than viscose and pigment of coursecould require either fewer or greater units for homogenization,depending on the material processed. The steel Wool serves to split upthe concentrated mixture introduced at pipe 40, thus insuring that thisparticular stream is completely homogenized by diffusion of the pigmentinto the high viscous liquid.

In an alternative construction, it is possible to introduce the materialin a rectangular or square conduit forming a stream composed of paralleladjacent layers. In this event, the baffles for dividing the stream intosectors would not be radial as shown at 17, but would extend in parallelalong planes normal to the longitudinal axis of the streams as viewed incross-section. The longitudinal axis of each layer of course would berotated 90 upon passage through a mixer unit, and the following mixerwould slice through at least two adjacent sectors in the mannerdescribed above.

If the liquids or materials to be blended are supplied in quantities ofthe same order of magnitude, the shunt system shown at 3 8, 40, etc., isnot necessary. Two main supply conduits such as 36 could be provided,with a transition area in one for supplying the material containedtherein to annular compartment 41.

A good homogenizing effect and thorough mixing is obtained if, accordingto this invention, the channels have a cross-sectional shape uponintroduction to a mixer unit which so changes upon discharge therefromthat the profile becomes more oblong. In other words, the quotient ofthe circumference and the square root from the area of these enteringand discharging cross-sections should increase.

Although the transition zone of a channel passing through each mixerunit has been shown to make rather abrupt changes (see FIGURES l and 4,for example), it is obvious that the surfaces could be rounded in orderto provide a more streamlined flow in the event such is necessary ordesired, such as when processing extremely high viscous material.Moreover, the mixer units may be formed from any suitable materials, forexample, by casting into an integral piece, or the separators could beformed individually in the manner of turbine blades and thereaftersecured to the supporting divider 18. In the latter case, a plurality ofidentical components could be constructed for subsequent assembly.Additionally, it is possible that the separators could be cast in halfsections. In this event, two separate molds would be necessary, sincealternate half sections would be mirror images one of the other.

Inasmuch as various other modifications will become apparent to thoseskilled in this art upon study of the preceding detailed disclosure, itis intended that the scope of this invention be limited only to theextent set forth in the accompanying claims.

What is claimed is:

1. A process for mixing at least two streams of flowing materialscomprising the steps of combining the streams into a single main stream,dividing the main stream into a plurality of partial streams, eachhaving major and minor axes in cross-section, and displacing at leastone partial stream with respect to an adjacent partial stream whilealtering the cross-sectional shape so as to reverse the major and minoraxes thereof.

2. A process for blending at least two streams of flowing materialscomprising the steps of combining said flowing streams into a first mainstream, dividing said first main stream into a plurality of firstsectors flowing adjacent to one another, each first sector having majorand minor axes in cross section, displacing each first sector withrespect to adjacent first sectors while changing the cross-sectionalshape to such an extent that the major and minor axes are reversed andeach first sector overlaps at least one adjacent sector, recombiningsaid first sectors into a second main stream, and thereafter dividingsaid main stream into additional sectors each receiving a portion ofmaterial from the space occupied by at least two of said overlappedsectors.

3. Apparatus for blending at least two streams of flowing materialscomprising means for combining said streams into a first main stream,means for dividing said first main stream into a plurality of firstsectors, each first sector having major and minor axes, means fordisplacing at least one of said first sectors with respect to adjacentfirst sectors while simultaneously changing the cross-sectional shapethereof to such an extent that the major and minor axes are reversed,means for recombinling said first sectors into a second main stream, andmeans for dividing said second main stream into a plurality ofadditional sectors, each receiving a portion of material from at leasttwo of said first sectors.

4. Apparatus for blending flowing materials comprising means for forminga first main stream of annular cross-section from concentric layers offlowing materials, means for dividing said first main stream into aplurality of channels disposed oircumferentially therearound, eachchannel having major and minor axes and each channel containing materialfrom each of said layers, means for displacing at least one of saidchannels with respect to adjacent channels while simultaneously changingthe cross-sectional shape thereof to such an extent as to reverse themajor and minor axes and overlie adjacent channels, means forrecombining said displaced channels into a second main stream, and meansfor dividing said second main stream into sectors each receiving aportion of material from at least two of said channels.

5. A mixing apparatus comprising an outer tubular conduit, an innertubular conduit, at least one mixer unit bridging the space between saidinner and outer tubular conduits, said mixer unit comprising an annulardivider concentrically mounted in the space between said conduits, aplurality of outer separators secured to the outer surface of saidannular divider, a plurality of inner separators secured to the innersurface of said annular divider in staggered relationship with respectto said outer separators, each of said outer and inner separators havinga wedgeshaped body portion terminating in an edge extending generallyradially of said annular divider, a radially extending baffle secured toeach side of said body portion, and means defining a sloping surfaceextending from one surface of said body portion between said baffles tothe opposite surface thereof.

6. A mixing apparatus comprising a conduit of uniform cross section forsupplying a main stream of unmixed materials to be blended, means withinsaid conduit for dividing said main stream into at least two partialstreams, means within said conduit for displacing one partial streamrelative to the others While simultaneously altering the cross sectionalshape of each, means within said conduit subsequent to said displacingmeans for at least once simultaneously sub-dividing each of said partialstreams into at least two sub-partial streams, the sub-partial streamsresulting from each sub-division corresponding in number to said partialstreams, means within said conduit for displacing each sub-partialstream relative to the others while altering the cross sectional shapethereof, and means within said conduit for directly combiningcorresponding subpartial streams into modified partial streams andmodified partial streams into a modified main stream to thoroughly blendsaid materials.

7. A mixing apparatus comprising a conduit of uniform cross section forsupplying a main stream of unmixed materials to be blended, means withinsaid conduit for dividing said main stream into first and second partialstreams, means within said conduit for displacing one partial streamrelative to the other while simultaneously altering the cross sectionalshape of each, means within said conduit for simultaneously subdividingeach of said partial streams into first and second sub-partial streamswhile again altering the cross sectional shape thereof, and means withinsaid conduit for directly combining sub-partial streams from the firstpartial stream with sub-partial streams from the second partial streamin corresponding pairs to produce modified first and second partialstreams.

References Cited in the file of this patent UNITED STATES PATENTS1,204,163 Kusebauch Nov. 7, 1916 2,094,948 Hurley et al. Oct. 5, 19372,230,221 Fitch Feb. 4, 1941 2,426,833 Lloyd Sept. 2, 1947 2,553,141Maynard May 15, 1951 2,554,167 Anderson May 22, 1951 2,869,837 PickinJan. 20, 1959 FOREIGN PATENTS 237,901 Germany Sept. 13, 1911 959,155France Sept. 21, 1949

